1. Field of the Invention
The present invention relates to making articles by thermoforming techniques, and more specifically to forming holes in such articles during the thermoforming process.
2. Description of the Prior Art
Thermoforming techniques have been successively used for molding thin-walled articles from plastic sheet material. To provide openings or holes in such thermoformed articles, it is customary to perform an additional, punching operation after the article has been formed.
Such punching operations involve the provision of extra equipment, such as a set of punches and dies at a punch station, means for transporting the formed articles to the punch station, and indexing means for locating the articles relative to the punching equipment. The cost of such extra equipment constitutes a considerable portion of the expenditure involved when setting up to manufacture this type of article. Also, the secondary, hole punching operation requires close tolerance indexing of the article at the punch station. In accordance with the present invention, a method and apparatus are provided for manufacturing thin-walled plastic articles from sheet material which eliminates the need for punching equipment and a secondary, hole punching operation.